Dresden 2026 – scientific programme
Parts | Days | Selection | Search | Updates | Downloads | Help
TT: Fachverband Tiefe Temperaturen
TT 5: Superconductivity: Sample Preparation and Characterization
TT 5.3: Talk
Monday, March 9, 2026, 10:00–10:15, CHE/0089
Superconducting resonators from ultrathin NbN films — •meenakshi sharma1, hrishikesh borah1, surinder singh2, sandeep singh2, haolin jin1, yejin lee1, and uri vool1 — 1MPI CPFS, Dresden, Germany — 2CSIR NPL, Delhi, India
We investigate superconducting microwave resonators fabricated from ultrathin niobium nitride (NbN) films with thicknesses down to 3 nm. Such films show extremely high kinetic inductance values of 298 pH per square, approaching the regime where disorder strongly influences superconductivity. However, they remain robust and exhibit a critical temperature of 7.8 K, making them suitable for high-impedance circuit applications. The resonators achieve internal quality factors of approximately 104-105, demonstrating that reliable device performance can be sustained even at such critical thicknesses. By monitoring the resonance frequency as a function of temperature, we probe the electrodynamic response of the ultrathin superconducting state. The superfluid density departs from the exponential temperature dependence expected for conventional BCS superconductors and instead follows a power-law behavior at low temperatures, indicating spatial inhomogeneity in the superconducting condensate. At millikelvin temperatures, dissipation is dominated by two-level systems, but the large kinetic inductance suppresses their influence on the resonance frequency, thereby enabling stable and reproducible devices. These results establish ultrathin NbN as both a practical platform for high-impedance quantum circuits and an accessible system for studying unconventional superconducting physics.
Keywords: Superconducting microwave resonators; Ultra-thin NbN films; High Kinetic Inductance; Power law; Granularity and Disorder